Briquets made of char and method for the production thereof



AUZ- 155.1957 w. C, SMITH 3,336,122

BRIQUETS MADE OF CHAR AND METHOD FOR THE PRODUCTION THEREOF Filed April28, 1964 INVENTOR. fav/f# United States Patent C) 17 Claims. (Cl.44--17) This invention relates to briquets made of char and method forthe production thereof. The present application is acontinuation-in-part of, and a substitute for, my application 225,093,tiled Sept. 20, 1962 and now abandoned as a substitute for abandonedapplication Ser. No. 187,042, led Apr. 12, 1962.

Most of the briquets presently available are bonded with cornstarch andcorn ilour and other relatively expensive materials. Unless speciallycoated, they are dirty to handle and they disintegrate readily in thepresence of moisture. The briquet of the present invention is so cleanthat it can be handled without soiling the users hands and it issubstantially non-absorbent of moisture and does not disintegrate in thepresence of moisture. These results are achieved by the use as a binderof a reaction product of sulphite liquor and an oxidizing agent such assodium nitrate, the latter being incorporated in quantities very greatlyin excess of those employed when the oxidizing agent is used solely tofacilitate combustion. The composition and method of manufacture of myimproved briquet make it practicable to use these materials withoutoffensive odor or other problems.

The improved briquet can be ignited readily despite Y the fact that ifthe binder is carbonized the briquet surface is so hard that it does notsoil the hands of the user and will not disintegrate in water. If thebinder is un-carbonized, the briquet is still superior even though itmay be no different from standard charcoal as to dusting ordisintegration when soaked.

Spent sulphite liquor is a by-product of the paper in-` dustry. Althoughthe product itself is well-known, its precise chemical composition isnot fully understood even by researchers in paper chemistry. It normallyhas a strong odor on burning which would make it unacceptable as acomponent ofva briquet used in cooking. However, I have diScovered'hoWto eliminate the odor substantially completely. Disposition of the spentsulphite liquor in paper mill waste has long been a major problembecause this material, if dumped into streams, chemically combines withthe oxygen in the water with the resulting death of marine lifedependent on oxygen. Currently, much of the spent sulphite liquor isbeing burned to get rid of it. The present invention gives value to thisWaste product.

As will hereinafter be explained, one embodiment of the inventioncontemplates the use of a special form of char which is also aby-product of the paper industry, being collected in the form of fly ashfrom the burning of bark and other waste wood products. Other forms ofchar are lignite char and coal char and wood char.

Also used in my improved briquet is a nitrate such as sodium nitrate.Other nitrates which are strong oxidizing agents can be substituted withdue allowance for nitrate mol equivalence. All examples herein usesodium nitrate but contemplate substitution of known oxidizing nitrateequivalents in proper chemical proportions.

3,336,122 Patented Aug. 15, 1967 Sodium nitrate has previously beenemployed in briquets in small quantities to promote ignition. Thequantities have had to be very limited because sodium nitrate is such apowerful oxidizing agent that if the quantities used in conventionalbriquets are very substantial, the briquets burn fiercely, emittingcopious quantities of sparks. Even the small amounts of nitrate commonlyused require the drying temperatures to be sharply limited lest thebriquets burst into llame.

The present invention is based on my discovery that if enough nitrate isused to react chemically with the sulphite liquor, very hightemperatures required to drive olf odorous components of the liquor maybe used without experiencing spontaneous combustion of charcoal whichhas heretofore been experienced when attempts have been made toaccelerate the drying of charcoal briquets or the carbonizing ofsulphite liquor without using inert atmospheres. Such combustion hasheretofore been experienced in attempts to dry 4charcoal or to carbonizesulphite liquors at temperatures in excess of 300 F. Thus, whereasoxidizing nitrates have heretofore been used to promote ignition, andthe quantities had to be severely limited, I use such nitrates inrelatively large quantities to oxidize theisulphite liquor. Theanomalous result is that instead of the fierce ignition heretoforeexperienced with much lower percentages of nitrate, I am able to dry thebriquets very quickly and at very high temperatures, thereby driving offodors, and without spontaneous combustion. The result is that I am ableto produce superior char briquets which ignite as readily asconventional charcoal or more so and without the grave hazardexperienced in igniting briquets -containing free or unreacted oxidant.

The nitrate may be incorporated in the mix either dry or in solution inthe water which is added. Assuming the nitrate is present in adequatequantities and the temperatures are adequate for substantially completechemical combination, the nitrate reacts in situ with the sulphiteliquor on the surfaces of the particles of char to make a better binderthan the sulphite liquor used alone. In practice this result is achievedwhether the nitrate is added Wet or dry.

The desired results are not achieved if the sulphite liquor and thenitrate are pre-mixed. lf desired, it is possible to carbonize thesulphite liquor to make the briquets water resistant. In any event,practically all of the objectionable odor of the sulphite liquor isdestroyed during drying, the remainder disappearing during the ignitionstages so that when the briquet is burning in the combustion requiredfor use in cooking, there is no odor left.

Some of the proportions involved are highly critical. It is evennecessary to take into account the nature of the product from which thechar is made. Even more important is the porosity and the content ofvolatile matter of the char.

The procedures involved can be performed entirely by hand or can becontrolled in part or in whole by hand even though the mixing is donemechanically. The entire operation is preferably controlledautomatically but the accompanying drawings show flow diagrams in whichboth batch mixing and continuous mixing are illustrated.

In the drawings:

FIG. 1 is a liow diagram for a method of manufacture using a batchmixing process manually controlled.

FIG. 2 is a ow diagram for a method of manufacture using a continuousand automatically controlled mixing process.

FIG. 3 is a fragmentary detail view on an enlarged scale of theextruding portion of a preferred plasticizer in axial section.

FIG. 4 is a detail view in elevation of the delivery end of theplasticizer.

The char used is in particles desirably averaging no more thanone-eighth or one-quarter inch in accordance with conventional practice.The resulting particles of char are porous and different chars havedifferent porosities based on their mode of being produced and theoriginal products from which they are made. This has a bearing on theprocedure as will be noted hereinafter.

One embodiment of the invention contemplates the use of so-called y ashcharcoal. This charcoal is already of small particle size. It is-produced in the combustion of bark and other waste. It is most oftenfound as a by-product in the operation of a pulp mill. Some mills feedbark and other waste into their `regular boilers while others usespecial boilers to dispose of the waste. In either case, the waste isused as fuel to generate steam used in the mill but there is an airpollution problem due to the large quantity of charcoal given off in theform of smoke and fly ash. In the past, this material has been collectedand is commonly re-injected into the boiler. For the purposes of thepresent invention, the collected material is screened to removeparticles of sand and ash and the resulting ily ash charcoal is used inthe manufacture of briquets.

Another embodiment contemplates use of ychar made from lignite or coalby drying and carbonizing to reduce water content and volatile matter.Carbonizing processes for making fuel chars as performed in standardmultiple hearth furnaces, properly controlled, are appropriate. Typicalcarbonizing retorts which are widely known and have been usedcommercially are the Badger-Stafford and Lurgi retorts.

Low porosity high density chars referred to herein are those weighingtwenty to thirty pounds per cubic foot. These include chars of coal andlignite. High porosity low density chars are those weighing ten totwenty pounds per cubic foot and include those made from wood, y ash ofsawdust and bark, peat and other vegetable matter.

To the particulate char, the nitrate is added. In the case of sodiumnitrate, the amount added is approximately twenty to thirty percent ofthe weight of the sulphite solids used as the binder. Twenty-fivepercent is ideal. If other nitrates are substituted, the amounts will bevaried in accordance with their mol value. The ingredients are mixedtogether. The nitrate may, if desired, be pre-mixed with the water.Otherwise the nitrate is mixed in dry form with the char and water isthen added in sufficient quantity to ll the voids or capillary openingsin the surfaces of the char particles. The amount of water should besuch that the total water ultimately present in the wet mix should beabout fourteen percent of the total wet weight for low por-osity charsand twenty percent of the total wet weight for high porosity chars. Therespective ranges are preferably about twelve to sixteen percent andeighteen to twenty-two percent. The term total water includes not onlythe amount added at this time but the water present in the concentratedsulphite liquor (about fifty percent of the weight of the liquor used)and the water present in the char itself (from about two to about tenpercent).

It is important that the free water added at this time must be in thechar before the sulphite liquor is added. Yet it is related to theamount of water in the sulphite liquor in such proportion that after thesulphite liquor has been introduced the total water will not besmallerthan twelve or eighteen percent respectively, or greater than sixteen ortwenty-two percent respectively, of the wet mix.

It will be noted hereinafter that low porosity chars also require thatsubstantially less sulphite liquor be used to effect binding. Inpractice, I use about half as much sulphite in low porosity chars as inhigh porosity chars.

While it is important that sufficient water be added in advance of thesulphite liquor to fill the voids or capillary openings, nevertheless itis important, particularly on high porosity chars, that extra water notbe present or the mix will be unable to assimilate suicient quantitiesof liquor to acquire bond strength. Also, too little Water presentallows the sulphite liquor to penetrate the char particle pores causingthe briquets to crack either during molding or drying. Proper watercontent allows the right amount of liquor t-o be utilized to effect goodsurface bonding without undue penetration of the char particles.

The fly ash charcoal above referred to is a high porosity char. Inpractice, my briquet mix contains about twenty percent total water whenmade with fly ash charcoal. About one-fifth of this represents freewater. The nitrate is preferably dissolved in the free water, although,particularly if the ultimate product is to be carbonized, the nitratemay be used dry.

The sulphite liquor as produced originally by a paper mill contains morethan fifty percent water. To assure that enough free water is present tofill the voids of the char before the sulphite liquor is added, Whilestill maintaining total water within the range indicated, the sulphiteliquor used in this process should be dried to about fifty percent waterbefore being added. The percentage is not highly critical sinceadjustment of the amount of free water may be made to compensate.

Before the sulphite liquor is introduced, the wet mix is stirred well todisperse the free water. The sulphite liquor comprising about fiftypercent water is then added in an amount such that in a normal productthe sulphite liquor solids represent from eight to twenty percent of thetotal mix weight on a dry basis. This is a critical relationship, beingdependent upon the porosity of the char and its volatile matter content.In practice, I prefer to use sulphite liquor solids in the proportion ofabout nine percent by weight with lignite char and about seventeenpercent with fly ash char.

In either case, the nitrate solids used amount to approximatelytwenty-five percent by weight of the solids of the sulphite liquor.

If there is too little sulphite liquor used, the briquet will lack wetand dry strength and will readily ignite spontaneously during the dryingprocess. If there is too much, the mix will be too sticky to handleconveniently during mixing or briquetting. Even with the proportions ofsulphite liquor specified as desirable, spontaneous combustion can beexpected to occur during high temperature drying unless the amount ofnitrate present is adequate to assure the desired chemical reaction.

Briquets made with two much sulphite liquor have poor appearance andtend to crack open during drying. However, even briquets requiring highsulphite liquor percentage for bonding (because of high porosity char)do not ordinarily exhibit cracking when burned. In the case of the y ashor lignite char, no cracking whatever has been experienced. Even if theycrack open, the briquets will not break in two and the portions of thebriquet separated slightly by the crack tend to retain their firmness iffull advantage has been taken of the principles herein disclosed.

After the sulphite liquor is introduced, the mix is stirred lightly. Itis subjected to moderate densication by compaction or plasticizing,maintaining uniform densityvwhile avoiding any such compaction as wouldreduce particle size needed for briquet strength. The plasticizingoperation can be performed manually but is desirably performed in aspecial extruder automatically controlled as hereinafter described. Theproperly plasticized mix has a dry appearance as its leaves the `dualheads in short, chip-like, tlat extrusions. In these extrusions, the mixis densilied and the components well distributed.

If the material were unduly compacted at this stage, the briquets wouldcrack in the Wet or dry state, as the compressed char particles try toreturn to their original shape. In the case of briquets made from flyash char, cracking is not a problem but undue compaction is to beavoided because of the difficulty of ignition. Ignition is facilitatedif compaction is very light. Disintegration during handling can beavoided by adding minute quantities of lime in any form. I have usedone-half of one percent of slaked lime added with the free water.

Also this plasticizing aligns and Orients, most advantageously, the sizerange of char particles to get maximum green, dry and burning strength.

The material is then briquetted in a conventional roll press having avertical screw or paddle stuler which forces the proper amount of mixinto each cavity of the press to mold a briquet with a tight surface forappearance and prevention of spontaneous ignition in the drier. Finally,the wet briquets are dried in a standard tunnel air drier underoperational conditions which may advantageously diler markedly frompresent practice.

The practice of my invention differs somewhat according to whether thebriquets are to be carbonized or not. Particularly in the case ofbarbecue briquets made from fly ash charcoal, it may be desirable toleave the briquet uncarbonized.

It is an important factor of the present invention that the desirablecarbonization of the binder which protects the briquet fromdisintegration in the presence of moisture is achieved, according to thepresent invention, without excluding oxygen and at temperatures soelevated and for such lengths of time that the binder is carbonized.

Heretofore, experimentally, at least, carbonization of briquets has beenperformed previously but has required exclusion of oxygen if thebriquets were held at temperatures as high as 300 F. for any appreciabletime.

Conventionally, starch or our bound wet briquets enter a drier with alow inlet temperature, about 250 F. and are gradually raised to amaximum temperature of about 300 F. to 325 F. in one hour. Thesebriquets are then maintained at such temperatures for one-half hour andthen cooled to an exit temperature of less than 200 F. in another hour.Total elapsed time in the drier is thus about two and one-half hourswith gradual heating and cooling and maximum time at high heat ofonehalf an hour. These conventional briquets must be heated slowly toprevent surface sealing and accompanying cracking during moisturerelease. They cannot be raised to temperatures much in excess of thosespecified and ,can be held for only a short period of time or thebriquets will spontaneously ignite. These briquets must also be cooledslowly to prevent cracking and the finished product may not leave thedrier with a temperature over 4200" F. for safety. Such drying asdescribed above requires a proportionally longer time and often thebriquets leave the drier with moisture content considerably greater thanthe accepted standard of four percent. This standard is recognized asthe maximum moisture limit allowable to preclude shipment of wet productto customers.

According to the present invention, there is no slow rise of temperatureand no limitation to 325 F. Charcoal briquets properly bound withsulphite liquor and nitrate as herein disclosed may enter such an airdrier at any temperature up to about 450 F. In fact, the preferredtemperature of the entire drier, even at the inlet, is 450 F. Drying andreacting takes about seventeen to twenty minutes. No surface sealing andcracking of the product occurs, as the briquet surface, althoughbecoming hard, maintains its porosity. Y

Assuming that the briquets are to be carbonized, they are thenmaintained at this temperature for about twenty minutes more to effectcarbonization. With high porosity char, forty minutes total exposure isabout the maximum. Within this period (or a much longer time with lowporosity char) there is no apparent tendency to ignite spontaneously.Total time in the drier thus averages from a minimum of about fifteenminutes to a maximum of about forty minutes or less.

To cool the briquets rapidly from 450 F., they are sprayed with a iinemist of water which reduces their temperature to F. in ten minutes.While the briquets of the present invention may be cooled conventionallyby subjecting them to a blast of cold air for about a half hour, it is agreat advantage to be able to cool them rapidly. The carbonized productis fully water lresistant and the uncarbonized product is not. However,if the water is used in the form of spray, it is possible to water coolboth products because they are so effectively bound that they resistcracking when rapidly cooled.

Prior to water cooling, the briquets have zero per cent moisture and dueto their high temperature, they absorb only about one to two per centmoisture on spray cooling. Further humidilication in moist atmosphere tothree per cent moisture may be done if desired.

The high drying temperature employed in this process not only reducesthe time in the drier (which is important commercially) without dangerof spontaneous ignition but almost completely drives out any sulfurousodors remaining in the reacted binder. Such odors have heretofore madeit impractical to use sulphite liquor as a binder for briquets of thetype used in cooking. The product of the present invention may give offsome slight odor during ignition but before it reaches the fullcombustion required for cooking, it has no remaining odor whatever.

Briquets previously known could not lbe dried and heated in the mannercontemplated by the present invention without igniting. Even at thetemperatures conventionally used in drying charcoal briquets, a briquetcontaining one per cent of nitrate by dry weight is extremely hazardous.When ignited, it will burn ercely and may spin like a pinwheel.

In the formula herein disclosed, almost all of the nitrate appears to-be used in oxidizing the sulphite liquor to improve its bindercharacteristics. Thus no excess of nitrate remains to cause re hazard.The oxidation of the sulphite liquor by means of the nitrate is a veryimportant factor in eliminating objectionable odor. If the nitrate isbelow twenty to twenty-tive per cent of the weight of the solids in thespent sulphite liquor, the briquets smell strongly. In fact, at leasttwenty-tive per cent is a desirable amount of nitrate.

If the product is fully carbonized, ignition is aided by having a slightexcess of nitrate uncombined in the briquet in dry form. If the binderin the product is to be uncarbonized it is not only unnecessary that thenitrate be added dry but it may even be undesirable because the dryparticles at the surface of the briquet tend to glow to a degree thatthey do not do if the nitrate has been completely dissolved in water andreacted with the sulphite liquor.

The fact that my improved briquets can be dried at high temperature'is avery important consideration in eliminating odor. The high temperaturetreatment, even in the case of the briquet with binder not fullycarbonized, is adequate to drive olf most of the objectionable odors. Bythis I mean that the sulfur compounds are converted to products such assulfur dioxide which is given off as a vapor or to sulphates or otherprecipitates which do not burn or give olf odor at the temperatures atwhich briquets are burned in barbecuing. However, excessivecarbonization will burn out the bonding material with the result thatthe briquet loses Weight-and strength. Experience shows that the briquetwith uncarbonized binder has higher strength than as if the binder iscarbonized, although its water resistance may be somewhat less.

If full advantage of the disclosures herein is taken, my improvedbriquets are clean since they do not dust or leave marks. They are verywater resistant if the binder is carbonized, being capable ofmaintaining their integrity even when immersed in water over longperiods. They are smokeless, this being a very desirable factor inbriquets made for barbecue usage. Finally, they are very strong whenburning as compared with previously known commercial briquets.

If the amount of nitrate solids present exceed thirty per cent of thesulphite solids, this will preset the sulphite liquor with the resultthat the sulphite liquor cannot be properly dispersed in the mix, andunreacted nitrate is present in the product.

The preliminary addition of free water in advance of adding the sulphiteliquor is to ll the voids of the char particles so that the binder whichis the reaction product of the sulphite liquor and the nitrate will beas much as possible limited to the surfaces of the char particlesinstead of being adsorbed deeply into the pores or capillary openingsthereof. Whether the nitrate is used dry or dissolved in water, thedesired reaction-product binder is quite largely on or close to thesurfaces.

The entire operation as above described can be performed either as abatch or a continuous process according to the iow sheets shown in thedrawings.

The batch mixing process A batch of char is placed in the container 6and to it is then added the dry nitrate carefully weighed to maintainthe proportions indicated. After the char and nitrate have been mixed bymeans of mixer `8, a carefully measured batch of water is introduced inthe proportions above speciiied and the mixing continued until the wetpre-mix is thoroughly homogeneous. In the alternative procedurediscussed above, the nitrate, proportioned by weight to the char, isincorporated in the water prior to the admixture of the water with thechar. Only at that point is the metered sulphite liquor added. Thewell-mixed batch is then dumped as indicated by the arrow 10 into thehopper 12 which feeds the paddle conveyor 14 driven by motor 16 undermanual control of rheostat 18.

At the discharge end of the paddle mixer 14, the material is deliveredas shown by arrow 20 into a plasticizing conveyor 22, which is preferredto a hand plasticizing operation because the densification of the mix atthis point is quite critical and it can be accurately controlled by theapparatus shown. Details of the discharge end of this conveyor are shownin FIGS. 3 and 4. A feed screw 24 driven by motor 26 `at speedscontrolled by rheostat 28 discharges material through a pair ofextruding dies 30 and 32 which have variably registrable openings 34 and36, respectively. FIG. 4 shows these openings in partial registry. Thedie 32 is rotatable within the retaining ring 38 by means of a crank pin40 and link 42. Clockwise rotation of the die disk 32, as viewed in FIG.4, will decrease the registration of the openings 34 and 36 whilecounterclockwise rotation will increase the openings. By increasing ordecreasing the composite openings, the density of the extruded mix maybe decreased or increased.

The density is automatically controlled by means of an instrument 44which has a pickup coil 46 associated with the line 48 to the motor 26.By means of this pickup coil, the instrument 44 senses the ampere loadon the motor 26, such load increasing as the mixture in the plasticizingmixer22 becomes denser. If the mixture becomes less dense, the load onthe motor decreases. Accordingly, the instrument 44, sensing the load onthe motor, controls a regulating motor 50 which corrects for any changein density by rotating the disk 32 to increase or decrease theregistration of ports 36 with ports 34.

The extrusions through the registering ports are kept in short chip-likeform by a blade 54 connected with the shaft extension 56 of screw 24. Asthe screw rotates, the blade 54 wipes across the inner surface of thestationary extrusion disk 30 to sever the extrusions of material passingthrough the several ports 34.

An additional conveyor section S8 receives the short extrusions beyondthe extruding die sets 30, 32 and remixes these into homogeneity beforethey are discharged as indicated by the .arrow 60 to be elevated by theelevating conveyor 62. The mix is delivered as indicated by `arrow 64into the hopper 66 of a conventional briquetting press. The briquettingpress rolls 68 and 70 are driven by motor 72, which may be controlledIas to speed by a rheostat 74 subject to controller 76. The controllerfunctions according to the response of low and high level probes 78 and80 in the hopper to increase the speed of the briquetting rolls as thedepth of rnix accumulating in the hopper is increased, and vice versa.The drive 82 from motor 72 operates the stuffer 84 which forces the mixinto the briquetting rolls 68, 70. The briquets discharged from thebriquetting rolls as indicated by arrow 86 are then taken to the tunneldrier above described.

The automatically controlled continuous process I can use either avibratory or a volumetric feeder at 90 driven by motor 92, which feedercontinuously delivers crushed char from the hopper 94 onto the scaleplatform conveyor 96 of a so-called weightometer. The weight of char onthe Weightometer is continuously impressed as indicated diagrammaticallyby the line 98 upon an instru- -rnent 100 which integrates the weightwith the moisture content of the char as lread by a moisture scanninginstrument 102. The reading of instrument 102 is communicated tointegrating instrument 100 as indicated by the dotted line 104. Areading representing the dry weight of the char is then communicated tothe master controller as indicated diagrammatically by line 106.

The master controller 110 regulates the functioning of an instrument 112to which it is connected as indicated diagrammatically by the line 114.The instrument 112 has a connection diagramm-atically indicated by line116 with a controller 118 for rheostat 120 which varies the speed ofmotor 92, the net effect of this arrangement being to maintain charinput feed at a constant dry rate.

The char fed at a uniform dry weight is discharged from the weightometerconveyor as diagrammatically indicated by arrow 122 to enter a pre-mixpaddle type conveyor 124 in which nitrate is now added. The nitratehopper is shown at 126 and the nitrate feeder at 128. The dotted line130 from controller 132 indicates that the controller regulates theoperation of the feeder. Such regulation is, in turn, controlled fromanother controller 136 as indicated by the broken line 138 andhereinafter described.

After the dry nitrate and the dry char have been mixed, water is addedto the mix in the paddle conveyor as indicated by the arrow 140. Thewater feeder is diagrammatically shown at 142. It is regulated by acontroller 144 as indicated diagrammatically by the broken line 146. Thecontroller 144 responds to several factors including the amount of wateralready present in the char as read by moisture scanner 102. It will beremembered that the scanner affects the operation of the instrument 100which debits the water flow controller 144 with the moisture alreadypresent in the char, the connection between instruments 100 and 144being diagrammatically indicated by the broken line 148. The instrument144 also responds to the flow of char on a dry weight basis as read bythe master controller 110, the value being communicated to theinstrument 144 as indicated diagrammatically by the broken line 150.

If the nitrate is to be added wet, the procedure varies from that abovedescribed in that the nitrate is simply 9 added from the feeder 128 tothe water instead of being added dry to the char. The mixture of thewater with the char, thereupon incorporates the nitrate in the charalong with the water.

After the wet pre-mix is complete, the spent sulphite liquor is added asshown by `arrow 152. This is carefully proportioned by a rotary pumpfeeder 154 whose operation is regulated by the instrument 136 andindicated diagrammatically by the broken line 156. Instrument 136 isalso responsive to the d ry weight of the char constantly fed from theweightometer into the mixer 124. The connection from the mastercontroller 110 to the instrument 136 is diagrammatically illustrated bythe broken line 158. If the nitrate is incorporated dry, it is thisinstrument that also proportions the dry nitrate feed as indicated bybroken line 138. If the nitrate is incorporated wet, it will alreadyhave been mixed with the water.

The paddle mixer shaft 160 may be driven by motor 162 manuallycontrolled by rheostat 164.

The operation from this point on is identical with that described inconnection with FIGS. 1, 2, 3 and 4.

It will be understood thatthe instruments will be adjusted to maintainthe proportions within the ranges indicated as critical and to produceuniformity of results.

'I'he product before drying has a moisture content approximatingfourteen percent in the case of lignite char and twenty percent in thecase of fly ash char as compared with twenty-eight to thirty-eightpercent moisture in conventional briquets. The finished product, priorto water cooling has zero percent moisture and as discharged from theapparatus has a total of only about two percent moisture. This compareswith prior practice in which the briquets leave the drier with amoisture content which may be greater than the accepted limit of fourpercent.

The final product of the present invention does not readily chip, anddoes not dust It can be handled without soil if the binder has beencarbonized. It is readily ignited, burns uniformly, is without odor whenin full combustion, `does not smoke, and with carbonized binder resistsdisintegration in the presence of moisture.

In View of the above noted fact that various components of the spentsulphite liquor including water and sulphur and other oxidizableelements are evaporated or consumed in processing, it will be understoodthat the reference to spent sulphite liquor as an ingreditent of thebriquet defined in the accompanying claims is intended to refer to theessential fractions of the sulphite liquor which remain in the reactionproduct which serves as the binder component of the briquet.

I claim:

1. A briquet for barbecuing food and containing char and a binder whichis a reaction product of an oxidizing nitrate and spent sulphite liquor,said briquet containing by weight eight to twenty percent of liquorsolids and the equivalent of approximately twenty-five percent as muchsodium nitrate solids as sulphite liquor solids.

2. A briquet containing char and a binder which is a reaction product ofan oxidizing nitrate and spent sulphite liquor the char comprisingdiscrete particles, the bonding material being primarily confined to thesurfaces of such particles.

3. A briquet yaccording to claim 1 in which the sulphite liquor solidsare present in the approximate amount of eight to ten percent yby weightof the dry weight of the briquet and the char is a low porosity char,the nitrate being the equivalent of sodium nitrate approximatingtwenty-five percent of the weight of the solids of the sulphite liquor.

4. A briquet according to claim 1 in which the sulphite liquor solidsrepresent Iapproximately fifteen to twenty percent of the dry weight ofthe briquet and the char is a high porosity char, the nitrate solidsbeing 10 equivalent to a percentage of sodium nitrate approximatingtwenty-five percent of the weight of the solids of sulphite liquor, thenitrate solids being used in general proportion to the density of thechars.

5. A briquet according to claim 1 which contains materially less thanfour percent moisture and has sulphite liquor solids proportioned to thedensity of the char and approximating at least about 8.5 percent of thedry weight of the briquet, and the nitrate is in proportions comparablein oxidizing value to sodium nitrate and in amounts which, in the caseof sodium nitrate, approximate twenty to thirty percent of the weight ofsolid content of the sulphite liquor.

6. A briquet according to claim 5 in which the nitrate is sodium nitrateand the solids represent approximately twenty-five percent of the weightof the solid content of the sulphite liquor.

7. A briquet according to claim 5 which is substantially free lof sulfurcompounds vaporizable in the combustion of the briquet, all componentsof the char and binder ybeing carbonized and the briquet beingmoisture-resistant, hard, free from dust, and free from odor when infull combustion.

I8. A method of making char briquets for barbecuing food which methodcomprises the steps of mixing 'with particular char free watersufiicient to fill voids and capillaries of char particles andthereafter adding spent sulphite liquor and reacting such liquor in situwith an oxidizing nitrate to form a binder precluded lby the wateralready in the particles from substantial entry into the voids andcapillaries of the char particles, and thereafter mixing the char andbinder, and subsequently briquetting the mix.

9. A method of making char briquets according to clai-m 8 in which thenitrate and char are pre-mixed dry before the Water is added.

10. A method according to claim 8 in which the nitrate is mixed with theWater before the Water is added to the char.

11. A method of making char briquets according to claim 8 in which themixing after spent sulphite liquor is added lightly densiies the mix toa degree calculated to disperse component ingredients of the mix and toorient char particles without undue compaction thereof in the briquet.

12. A method according to claim 8 followed by ldrying for approximatelytwenty minutes in air at temperatures which materially exceed 400 F. toproduce a product in which the Abinder is carbonized and from whichodorous components are substantially eliminated.

13. A method according to claim 12 in which the drying is at atemperature at least approximately 450 F.

14. A method according to claim 12 followed by rapid cooling by sprayingthe briquets with water mist.

15. A method of making for food -barbecuing purposes char briquets froma wet briquet mix which method comprises making a pre-mix of particulatechar and water, adding to the pre-mix an oxidizing nitrate in an amountequivalent in oxidizing value to sodium nitrate which comprises twentypercent to thirty percent by weight of the solid component of the spentsulphite liquor hereinafter mentioned, the water being in ya range ofproportions of twelve to twenty-two percent of the total wet briquet mixweight; thereafter completing the briquet mix by adding spent sulphiteliquor approximating fty percent water content in an amount such thatthe total solids in the spent sulphite liquor will be within a range ofeight to twenty percent of the weight of the dry components of thebriquet mix; plasticizing the briquet mix to .achieve moderatedensiication short of undue reduction in the particle size of the char,and thereafter driving off water and reacting the sulphite 11 12 liquorwith the nitrate on the surfaces of the char par- References Citedticies to form a reaction product -binder by heating the FOREIGN PATENTSbriquet m1x at temperatures materlally m excess of 400 F. to completesaid reaction Without combustion. 470,477 1/1929 Germany- 16. A methodaccording to claim 15 in which the ni- 5 OTHER REFERENCES trate is addedto the water in advance of mixing with the Char. Handbook of Brquettingby Franke, v01. 1, Grin and 17. A method according to claim 1s in whichthe bri- CO-Ltd-Londom1917PP'45 and 46- quets are dried and heated Whileexposed to air .at teml. peratures approximating 450 F. to 460 F. untilsaid 10 DANIEL E'WYMANPHmmy Exammer' binder is carbonized. C. F. DEES,Assistant Examiner.

1. A BRIQUET FOR BARBECUING FOOD AND CONTAINING CHAR AND A BINDER WHICHIS A REACTION PRODUCT OF AN OXIDIZING NITRATE AND SPENT SULPHITE LIQUOR,SAID BRIQUET CONTAINING BY WEIGHT EIGHT TO TWENTY PERCENT OF LIQUORSOLIDS AND THE EQUIVALENT OF APPROXIMATELY TWENTY-FIVE PERCENT AS MUCHSODIUM NITRATE SOLIDS AS SULPHITE LIQUOR SOLIDS.